Leaf drip

Ross Koning koning at ECSUC.CTSTATEU.EDU
Thu Nov 13 15:09:37 EST 1997


At 4:13 PM -0500 11/12/97, John Hewitson wrote:
>The leaves are falling here in England too.  All at once, with the first
>frosts of the winter this last fortnight.
>
>Under our Wallnut trees (Juglans regia) I find there is no moss growing
>amongst the cobbles until outside the leaf-drip zone where a healthy carp=
=3D
>et
>of moss has grown.  I doubt whether this is due to lack of light (the
>lowest branches are 10 ft up), I suspect that the amount of moisture is n=
=3D
>ot
>very different either.  I have observed this under Holly (Ilex aquifolium=
=3D
>)
>too, where Winter aconites (Eranthis hyemalis) do not grow under the tree=
=3D
>
>until clear of the leaf-drip.  Aconites do however grow under a Beech tre=
=3D
>e
>(Fagus sylvatica).
>
>Is this a well known fact, if so what is the explanation.  Otherwise, wha=
=3D
>t
>do you think?  Are there inhibitory chemicals in the water dripping off
>SOME leaves?


The popular choice for answering your question is
a chemical known as juglone that leaches from
leaves, bark, and fruit coverings of walnut.

ross

_______________________________________________________________
Ross Koning                 | koning at ecsu.ctstateu.edu
Biology Department          | http://koning.ecsu.ctstateu.edu/
Eastern CT State University | phone: 860-465-5327
Willimantic, CT 06226 USA   | fax: 860-465-4479
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